This invention relates to an aerial refueling system and more particularly but not by way of limitation to a microwave rendezvous system for use on a tanker aircraft for aerial refueling of a receiver aircraft.
Heretofore, the rendezvous of a tanker aircraft with a receiver aircraft for the purpose of air refueling was a difficult task in the best weather conditions. Both the tanker navigator and the receiver pilot must direct much of their attention to precise navigation, critical timing and speed control in order for visual contact to be obtained for the refueling operation.
In adverse weather aerial refueling may be virtually impossible. Even in cloudless daytime weather some rendezvous missions have been unsuccessful because the receiver pilot was unable to visually find the tanker. There has also been at least one incident involving a receiver aircraft colliding into the tailend of a civilian aircraft at night because the receiver pilot had mistaken the aircraft for a tanker. The rendezvous mission provides a burden of attention-consuming navigation and timing and yet this information may fail to guide the receiver pilot close enough to safely find the tanker. To add to this complexity, in war-time situations, ground-based navigational aids and radio transmissions cannot be used.
Currently a complex method of navigational procedures for a rendezvous mission is used by the airforce. The method employs the use of inertial navigational system (INS), air-to-air ground radar, air-to-air radar, air-to-air TACAN, drift angle true air-speed (TAS), or any combination thereof. There are various rendezvous patterns for different missions and receiver aircraft types, but the goal of each method is to position the receiver aircraft 2-3 miles behind and 1,000 feet below the tanker. Using INS, air-to-ground radar, and air-to-air radar demands considerable time and concentration from both the tanker navigator and the receiver pilot and/or navigator. Monitoring the TAS, drift angles, offset position, estimated time of arrival (ETA) to air refueling initial point (ARIP), course, and ETA to the air-refueling contact point (ARCP) is difficult, to say the least. Even if all the systems are working properly, it remains a major task to position the tanker and receiver aircraft at the proper position at the proper time, flying at the proper speeds.
Additional problems include the limitations of the TACAN and radar systems. On the KC-135 tankers, the TACAN provides range only. At best, the TACAN can assist the receiver pilot to about 1/2 mile from the tanker aircraft. Likewise, the air-to-air radar is unusable within 1/2 mile. In adverse weather, these limitations would make a successful rendezvous highly unlikely. Also, the only elevation information the receiver pilot has with reference to the tanker is based solely on altimeter readings.
TACAN and radar transmission broadcast electromagnetic radiation and are virtually omnidirectional. This enables easier detection by electronic sensors of potential enemies which during a war-time situation would be highly undesirable.
In the following U.S. Patents: U.S. Pat. No. 2,157,122 to Dunmore; U.S. Pat. No. 3,052,882 to Pidhayny et al; U.S. Pat. No. 3,285,544 to Chope et al and U.S. Pat. No. 4,128,839 to McComas various types of refueling systems are disclosed. None of these patents point out the particular unique features and advantages of the subject system as described herein.